This invention relates generally to farm implements and relates more particularly to towable implements for picking rocks from soil.
Prior art rock pickers have included types mounted to tractors including means for loading rocks into a rake or scoop together with means for raising the rake and dumping the stones from the raised position of the rake as shown by Weigel in U.S. Pat. No. 2,763,975. Weigel shows a scoop equipped with a rake having pointed teeth. In U.S. Pat. No. 2,812,029 Sund shows a towable rock picker having tines driven by a pair of chains which pass over sprockets. Sund arranges the chains so that rocks are caused to fall from the tines into a bucket.
Fraske discloses a rock picker having a pickup reel with teeth mounted thereon in U.S. Pat. No. 3,599,724. The teeth rotate continuously and sweep substantially parallel with the ground for a considerable distance thus facilitating the picking action. Fraske shows tracks and cam followers to control the position of stone pickup assemblies. A tractor mounted, ground-raking and rock-gathering apparatus is shown in Pat. No. 3,637,024 by Baskett. Baskett shows arcuately shaped teeth driven by a set of chains mounted on two sets of three guide sprockets. In Baskett's invention, the teeth rake the ground, gather the rocks and other debris and move it into a bucket. The bucket used is a conventional one attached to a front end loader type tractor. Hydraulic cylinders to raise and lower a sand cutting blade used in a beach cleaner apparatus is shown by Teixeira in U.S. Pat. No. 4,014,390. The sand cutting blade extends downward from the beach cleaner chassis at an oblique angle with respect to the surface of the sand and has a variable angle of attack.
U.S. Pat. No. 4,040,490 was granted to the instant inventor and shows a rock windrower having an elongated rake structure for windrowing surface rocks.